fix: handle unset keys in associative arrays to prevent set -u errors

validate_command_access.sh

@@ -68,14 +68,14 @@ validate_command() {
 
     declare -A seen=()
     for a in "${args[@]}"; do
-      [[ -z "${allowed_set[$a]}" ]] && {
+      if [[ -z "${allowed_set[$a]+_}" ]]; then
         echo "ERROR: Invalid argument '$a' for '$cmd'; allowed: (${allowed[*]})" >&2
         return 1
-      }
-      [[ -n "${seen[$a]}" ]] && {
+      fi
+      if [[ -n "${seen[$a]+_}" ]]; then
         echo "ERROR: Duplicate argument '$a' for '$cmd'" >&2
         return 1
-      }
+      fi
       seen["$a"]=1
     done
     return 0